E-Tree topologies often include various Provider Edge (PE) routers that communicate with one another over a MultiProtocol Label Switching (MPLS) network. In such topologies, the PE routers may each host all or a portion of one or more bridge domains consisting of logical ports that share the same flooding and/or broadcast characteristics. Unfortunately, depending on their respective configurations, some of these bridge domains may be unable to consume certain Broadcast, unknown Unicast, and Multicast (BUM) traffic sent over the MPLS network. As a result, the egress PE routers that host such bridge domains may end up dropping that type of BUM traffic, thus leading to superfluous bandwidth and/or resource usage within the MPLS network.
As a specific example, a traditional MPLS network may have a variety of PE routers, including first and second PE routers each configured with a leaf-only bridge domain, a third PE router configured with a root-and-leaf bridge domain, and a fourth PE router configured with a root-only bridge domain. As defined in the IETF's specification document, leaf bridge domains may be able to communicate with root bridge domains but unable to communicate with one another. Accordingly, in this traditional MPLS network, the first PE router may send out a multicast communication destined for each of the second, third, and fourth PE routers. However, while the root bridge domains on the third and fourth PE routers may be able to consume the multicast communication, the leaf-only bridge domain on the second PE router may be unable to consume the multicast communication. As a result, the second PE router may simply drop the multicast communication even though the multicast communication has already travelled over the MPLS network from the first PE router to the second PE router.
The instant disclosure, therefore, identifies and addresses a need for apparatuses, systems, and methods for preventing multicast traffic drops at egress routers in E-tree topologies.